Dental air abrasive system

ABSTRACT

Improvements are provided for a dental air abrasive system of the type which utilizes a compressed gas or air which creates a gas stream. Abrasive particles are introduced into the gas stream and expelled out through one end of a nozzle whereupon the abrasive laden gas stream impinges upon the target, i.e. tooth amalgam, composites, stain and/or tooth dental filling materials. The improvements include the use of two or more hoppers each containing different sized abrasive particles, which are selectively fed, either together or independently of each other, into the gas stream. Different sized abrasive particles are provided in each hopper for cutting different types of tooth structures. Other improvements include the use of fluorescent and/or colored abrasive particles to facilitate the aiming process, a laser beam, strobe, white light or other illuminating means for aiming the abrasive stream and/or illuminating the target area as well as a disposable nozzle for hygienic reasons. Other improvements include the use of a vacuum evacuation system to minimize dusting of the abrasive particles, as well as a dam removably positioned within the patient&#39;s mouth which reflects the abrasive particles back towards the evacuation system. Still other improvements include the use of a microvalve adjacent the nozzle which, when closed, terminates gas flow through the fluid passageway in order to further minimize dusting of the abrasive particles.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to dental air abrasive systemsfor removing and/or cutting tooth structure, amalgam, composites, otherdental tooth filling materials and/or stain.

II Description of the Prior Art

There are a number of previously known air abrasive systems which havebeen used in dentistry for cutting tooth structure, such as enamel anddentin. These previously known air abrasive systems typically comprisean elongated tube having a nozzle at one end and having its other endcoupled through a valve to a source of compressed air. Additionally, ahopper containing abrasive particles, such as aluminum oxide, are fedinto the fluid passageway between the compressed air source and thenozzle. Thus, with the valve open, the compressed air creates anabrasive particle laden air stream which is expelled outwardly throughthe end of the nozzle. When this abrasive particle laden air stream isdirected so that it impinges upon the tooth structure, cutting of thetooth structure results.

Although such dental abrasive air systems have been known for manyyears, they have not enjoyed widespread use or acceptance for a numberof different reasons. One reason for the commercial failure of thesepreviously known dental air abrasive systems is that such systems createa "dusting" around the work area. While such abrasive particles aremedically harmless, they do create an untidy and undesirable conditionfor the patient.

A still further disadvantage of these previously known dental airabrasive systems is that it was difficult to properly aim the effluentfrom the system nozzle. If improperly aimed, inadequate and imprecisecutting of the tooth structure can result or, alternatively, cutting ofthe wrong tooth structure and/or overcutting of the tooth structure.

A still further disadvantage of these previously known dental airabrasive systems is that typically only one size of abrasive materialcould be fed into the air stream. In practice, however, different typesof abrasive materials and/or different sizes of abrasive materials aremore desirable for different dental applications.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a number of improvements in dental airabrasive systems which overcome all of the above mentioned disadvantagesof the previously known devices.

In brief, the air abrasive system of the present invention comprises asource of compressed gas, preferably air, having its outlet connected toa valve. An elongated flexible tube also has one end connected to thevalve and a nozzle at its opposite end. Thus, once the valve is opened,compressed air flows through the flexible tube and out through thenozzle.

At least one, and preferably two hoppers are provided for introducingabrasive material into the gas flow stream through the flexible tube.When two hoppers are employed, different sized and/or colors and/ortypes of particles can be contained within each separate hopper. Then, acontrol system is employed to selectively introduce abrasive materialfrom either or both of the hoppers into the gas flow stream. In doingso, the abrasive particles can be selected in dependence upon theparticular dental application desired.

A number of improvements are provided for enhancing the aimingcapability of the abrasive material laden gas flow stream through thenozzle and/or illumination of the target area. In one embodiment of theinvention, a portion of the abrasive particles in either or both of thehoppers are made of a fluorescent or colored material. This fluorescentor colored material thus enhances the visibility of the gas flow streamand the impingement of the abrasive particles on the tooth structure forenhanced aiming capabilities.

Furthermore, as used in this patent, the term "tooth structure" includesnot only the tooth but also amalgam, composites, other dental fillingmaterials, stains, and/or other materials associated with the tooth.

In a further embodiment of the present invention, a laser beam, such asa continuous wave helium-neon laser beam has its output connectedthrough a fiber optic so that the laser beam is in alignment with thedischarge of the abrasive laden gas stream from the nozzle.Alternatively, a white light or a strobe light is used to illuminate thedischarge from the nozzle and/or the target area to facilitate aimingthe air abrasive system.

In order to minimize dusting caused by the abrasive material, a vacuumsystem is provided for evacuating the abrasive material afterimpingement of the abrasive material on the tooth structure. In thepreferred embodiment, the evacuation system comprises a relatively smalltube having an open end adjacent the target site. Thereafter, a largerdiameter evacuation tube is positioned outside of the patient's mouthwhile both the large and small tubes are connected to a vacuum sourceThus, abrasive materials which escape the vacuum created by the smallertube adjacent the target site are evacuated by the larger diameter tubeoutside of the patient's mouth thereby minimizing dusting of theabrasive material Additionally, a dam is preferably removably positionedwithin the patient's mouth which deflects abrasive materials from thepatient's mouth back towards the evacuation system which minimizes notonly dusting, but also the accumulation of abrasive material within thepatient's mouth.

In a further embodiment of the present invention, a fluid valve ispositioned closely adjacent the nozzle at the discharge end of the tubeThis valve, when closed, thus prevents the further discharge of abrasivematerials out through the nozzle which also minimizes dusting of theabrasive material.

Still further improvements comprise the use of a disposable nozzle forhygienic purposes.

Still further advantages and improvements will be subsequentlydescribed.

BRIEF DESCRIPTION OF THE DRAWING

A better understanding of the present invention will be had uponreference to the following detailed description when read in conjunctionwith the accompanying drawings, wherein like reference characters referto like parts throughout the several views, and in which:

FIG. 1 is a diagrammatic view illustrating a preferred embodiment of thepresent invention;

FIG. 2 is a partial diagrammatic view illustrating a portion of thepreferred embodiment of the present invention;

FIG. 3 is a diagrammatic view illustrating still a further preferredembodiment of the present invention;

FIG. 4 is a diagrammatic view illustrating the removable nozzle of thepresent invention;

FIG. 4A is an elevational view illustrating an alternate nozzle design;

FIG. 5 is a diagrammatic view illustrating the preferred embodiment ofthe evacuation system to minimize dusting;

FIG. 6 is a fragmentary view illustrating a further modification of thepresent invention;

FIG. 7 is a diagrammatic view illustrating yet a further embodiment ofthe present invention; and

FIG. 8 is a fragmentary diagrammatic view illustrating a furtherembodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

With reference first to FIG. 1, a preferred embodiment of the airabrasive system 10 of the present invention is thereshown and comprisesa pressurized gas or air source 12 having its output connected as aninput to an electrically actuated valve 14 Although any compressed gascan be employed in the compressed gas source 12, preferably compressedair is used.

Although any source of pressed gas 12 can be used with the presentinvention, most dental offices throughout the United States andelsewhere are equipped with a source of compressed air having a pressurebetween 80 and 120 psi which can be used as the source 12 of compressedgas. In some applications, however, it has been found that increasedpressures of about 160-200 psi are required for most efficient removalof tooth structure such as enamel and/or amalgam.

Therefore, in the preferred embodiment of the invention, a pneumaticamplifier 13 is provided in series with the output from the compressedgas or air source 12. This pneumatic amplifier 13 effectively increasesthe pressure from the source 12 to a pressure in excess of 120 psi, andpreferably in the range of 160-200 psi. The actual pressure is selectedby the operator or dentist in the fashion to be subsequently described.

The outlet of the valve 14 is connected to a fluid passage means 16which includes, at its distal end, a flexible tube 18. A control system20 controls the actuation of the valve 14 while a foot lever 22, orother actuating means, provides an input signal to the control system 20which, in turn, opens the valve 14. With the valve 14 open, thecompressed gas source 12 provides fluid flow through the fluidpassageway 16 and out through a nozzle 24 at the distal end of the fluidpassage means 16.

Still referring to FIG. 1, at least one, and preferably two hoppers 26and 28 are provided for selectively introducing abrasive material intothe gas flow stream through the fluid passageway 16. Preferably, thehoppers 26 and 28 are selectively connected by feed valves 30 and 32,respectively, to a mixing chamber 34. An output from the mixing chamber34 is open to the fluid passage means 16 so that, with the valve 14 openand the mixing chamber 34 introducing abrasive material into the gasflow through the fluid passage means 16, an abrasive material ladeneffluent 36 is discharged out through the nozzle 24 and towards a targetsite 38 on the tooth structure.

The hopper feed valves 30 and 32 are preferably electric solenoidactuated valves controlled by the control system 20. The control system20, furthermore, includes input means 40, such as a keypad, toselectively open either or both of the valves 30 and/or 32.

The use of two hoppers 26 and 28, each containing abrasive material,allows each hopper 26 and 28 to be filled with different types ofabrasive materials. These different types of abrasive materials caninclude, for example, abrasive materials having different particlesizes, different colors or other different characteristics. For example,one hopper 26 can contain abrasive material having an average size of20-35 microns while the second hopper contains an abrasive materialhaving a larger average size of 45-55 microns. The abrasive material isthen selected through the control means 20 for different dentalapplications.

Alternatively, three or even more hoppers, each containing differenttypes of abrasive materials can be used.

In addition, at least one of the abrasive materials has a majority ofabrasive material particles with an average size of 45-55 microns and,preferably, in excess of 95% of this material has a particle size ofbetween 45 and 55 microns. Preferably, the abrasive material comprises afused white, rolled crushed aluminum oxide which has jagged edges forgood cutting capability Alternatively, the abrasive particles can bemanufactured by jet milling. One or both of the hoppers can also containa flavoring, such as a mint flavoring, to reduce any unpleasantness fromthe taste of the abrasive particles in the patient's mouth.

With reference now to FIGS. 1 and 6, where two hoppers 26 and 28 areused to supply different types of abrasive material to the gas or airstream, in some cases it is desirable to eliminate the mixing chamber 34and instead introduce the abrasive material directly from the hopper 26or 28 into the fluid passage means 16. Furthermore, in order to switchvirtually instantaneously from one abrasive material in one hopper 26 tothe other abrasive material in the other hopper 28, two hoses 100 and102 form the fluid passage means 16. Furthermore, the material from onehopper 26 is introduced directly into the hose 100, while, similarly,the abrasive material from the other hopper 28 is introduced into thesecond hose 102.

The hoses 100 and 102 are interconnected by a Y junction 104 having aninternal flapper valve 106 which opens and closes the hoses 100 and 102in a mutually exclusive fashion. A disposable handpiece 108 having itsnozzle 24 is then detachably secured to the Y junction 104.

In practice, when abrasive material from the hopper 26 is desired, thegas stream with the abrasive material from the hopper 26 is suppliedthrough the hose 100, through the Y junction 104 and out through thehandpiece 108. At the same time, the flapper valve 106 closes the secondhose 102. Conversely, when abrasive material from the second hopper 28is desired, the gas stream laden with the abrasive material from thehopper 28 is provided through the tube 102, through the junction 104 andto the disposable handpiece 108.

A primary advantage of the embodiment of the invention illustrated inFIG. 6 is that, by the use of two separate hoses 100 and 102 for thedifferent types of abrasive materials, the dentist can virtuallyinstantaneously change from one abrasive material to the other abrasivematerial as opposed to a one hose system where abrasive materials may beentrapped within the hose and must be expelled before the newly selectedabrasive material is discharged from the nozzle 24. Furthermore, asingle detachable and disposable handpiece 108 can be used with eachpatient even though different types of abrasive material are used withthe same patient.

Referring to FIGS. 4 and 6, the disposable nozzle 108 preferably has anozzle 24 which is conically tapered and pointed to reduce clogging ofthe nozzle 24 and to reflect the deflection from a flat faced nozzle.Furthermore, either the nozzle 24 and/or the handpiece 108 should beconstructed of metal which resists wear during operation of the airabrasive system.

Nozzle shapes other than conical can also be used. For example, as shownin FIG. 4A, a nozzle 120 having a rectangular outlet 122 with a lengthto height ratio greater than ten is particularly useful for undercuttingthe tooth in preparation of a dental filling. Still other shapes, suchas a square nozzle outlet can also be used.

Still referring to FIG. 6, a tactile probe 110 can also be attached tothe nozzle 24 which acts as a feeler probe to space the nozzle from thetarget area by a predetermined distance, such as 1-2 mm from the nozzleorifice. The probe 110 thus allows an optimal working distance from thetarget area and readily allows the dentist to detect the depth of thecut being made on the tooth structure.

In order to enhance the visibility of the effluent 36 during the cuttingoperation, a portion of the abrasive materials in one or both of thehoppers 26 is made of a fluorescent and/or colored material Furthermore,although two hoppers 26 and 28 are disclosed in FIG. 1, it will beunderstood that alternatively, only one hopper containing one abrasivematerial can be used in the air abrasive system of the presentinvention.

With reference now to FIG. 3, a still further means for illuminating theabrasive material laden effluent 36 and/or target area is thereshown andcomprises an illumination source 50 having its output coupled by anoptical fiber 52 so that the output end 54 of the optical fiber 52 is inalignment with the effluent 36 from the nozzle 24. Thus, as shown inFIG. 3, the end 54 of the optical fiber 52 is positioned within thefluid passageway 56 formed by the tube 18 adjacent the nozzle 24.

Different types of illumination means 50 can be used for aiming theeffluent 36 and/or illuminating the target site. In a preferredembodiment of the invention, however, the illumination means 50comprises a helium neon laser which provides not only an illuminationmeans for the effluent 36 but also a means for aiming the effluent 36 atthe target site 38 on the tooth structure.

Other types of illuminating means 50 can alternatively be used. Theseother types include, for example, a bright white light which isreflected by the abrasive particles in the effluent 36, or a strobelight to facilitate both aiming of the effluent 36 and illumination ofthe target site 38. Mixing a portion of abrasive material havingdifferent colors can also be used to enhance aiming of the effluent.

With reference now to FIG. 4, a preferred embodiment of the nozzle 24 isthereshown. Preferably, the nozzle 24 is detachably secured to thedistal end 60 of the tube 18. Any conventional means, such as a snapfit, can be used to detachably secure the nozzle 24 to the flexible tube18. Preferably, the nozzle 24 is disposable for hygienic reasons.Alternatively, the entire handpiece, including the nozzle, is bothdetachable and disposable The nozzle 24 also includes means, such as abreakaway tab, which prevents the reattachment and reuse of the nozzle24 to thereby enhance patient safety by minimizing transmission ofgerms.

The present invention further provides several means for minimizingdusting of the abrasive particles during a dental therapeuticapplication. As best shown in FIG. 2, one preferred embodiment of thepresent invention utilizes a microfluid valve 62 which is provided inseries with the fluid passageway 16 closely adjacent the nozzle 24.Preferably, the valve 62 is electrically actuated and is controlled by acontrol line 64 to the control circuit 20. Thus, with the valve 62 in anopen position, gas flow through the fluid passageways 56 and out throughthe nozzle 24 as shown at 36 is established. Conversely, with the valve62 moved to its closed position, the discharge of the abrasive materialladen effluent 36 from the valve 24 is immediately terminated therebyminimizing dusting.

With reference now to FIG. 5, a preferred embodiment of an evacuationsystem 70 to minimize dusting is thereshown and comprises a small tube72 having an open end 74 and a larger diameter tube 76 having an openend 78. Both of the tubes 76 and 72 are connected to a vacuum source 80which, when actuated, inducts air flow, together with abrasive materialparticles, through the tubes 76 and 72 and to a collection bin 82.

Still referring to FIG. 5, the small tube 72 protrudes coaxiallyoutwardly from the larger tube 76 so that the end 74 of the small tube72 can be positioned adjacent the target site 38 in the patient's mouth.Conversely, the open end 78 of the larger tube 76 is positionedexteriorly of the patient's mouth and evacuates any materials which arereflected past the smaller tube 72 and outwardly from the patient'smouth.

Preferably, a removable dam 84 is removably positioned within thepatient's mouth and is designed to reflect abrasive materials backtowards the evacuation tubes 72 and 76. Thus, the dam 84 both minimizesdusting as well as the accumulation of the abrasive material within thepatient's mouth. Although such abrasive material is medically harmless,it does produce an undesirable chalky taste in the patient's mouth. Aflavoring, such as a mint flavoring, can also be added to the abrasivematerial to enhance the patient's comfort.

Dusting can also be reduced by constructing the delivery tube 18 from aflexible but inelastic material, or by providing additional structure,such as wrapping the tube 18, to minimize or eliminate its elasticity.Thus the volume of the tube 18 remains the same despite pressurizationof the tube which, in turn, minimizes dusting.

With reference now to FIG. 8, a still further means is thereshown forreducing dusting of the abrasive material after impingement of thetarget site 38 on the tooth structure. As shown in FIG. 8, a handpiece130 directs an abrasive material laden gas stream 132 toward the targetsite 38. The handpiece 130 also includes means 134 for forming a conicalwater spray 136 which surrounds and encloses the stream 132 at thetarget site 38. Thus, after impinging on the target site 38, theabrasive material forms a slurry with the water which is then evacuatedfrom the patient's mouth by conventional liquid dental evacuators (notshown).

With reference again to FIG. 1, the control system 20 preferablyincludes a time delay circuit 90 which automatically terminates gas flowthrough the fluid passageway 16 after a predetermined time period, suchas one second. Thus, following actuation or opening of the valve 14(FIG. 1) and/or the valve 62 (FIG. 2) the time delay circuit 90 willautomatically close the valve 14 and/or 62 following the predeterminedtime period In order to reinitiate the gas flow through the air abrasivesystem, the actuating means or pedal 22 must again be depressed. Thedelay circuit 90 thus minimizes the chance of overcutting of the toothstructure.

Although a foot lever or pedal 22 is illustrated as the means forinitiating the air abrasive stream, other actuating means canalternatively be used. These other means include, for example, valveactuating means contained on the handpiece, a hand operated controlpanel or the like.

Still referring to FIG. 1, a dentist or other operator of the airabrasive system can also use the keypad 40 on the control circuit 20 toinput a predetermined amount of grit to be released into the gas flowstream during each actuation of the pedal 22. Furthermore, the keypad 40is used to select which hopper 26 or 28 if multiple hoppers areemployed, for supplying the abrasive material to the gas flow stream.The keyboard can also be used to adjust the amount of abrasive materialintroduced into the gas flow stream during a specific time period.

The keypad can also be used to adjust the pressure and/or rate ofintroduction of abrasive material into the gas stream in accordance withthe desired rate of removal of the tooth structure.

A pressure regulator 100 is also preferably connected in series betweenthe source 12 of compressed gas and the valve 14. This pressureregulator 100 is controlled by the control circuit 20 through thekeyboard 40. Thus, the operator of the air abrasive system can adjustthe pressure of the gas from the source introduced into the fluidpassageway 16 in order to accommodate different types of dentalprocedures. For example, the removal of enamel may require a certainpressure, for example 120 psi, for most efficient removal while theremoval of amalgam would require a different pressure, for example 150psi, for most efficient removal.

With reference now to FIG. 7, a still further modification of thepresent invention is thereshown for an abrasive material laden gasstream for use with multiple work stations. As shown in FIG. 7, a mainabrasive system 120 introduces an abrasive material laden gas streaminto a circulating loop 122. The gas in the loop 122, together with itsentrained abrasive material, is continuously recirculated throughout theloop 122 by a recirculating means 124, such as a gas pump.

At least two, and preferably more remote stations 126 are provided fordelivering the gas stream at remote locations. Each remote station 126comprises a valve 128 which is actuated at the remote station by aswitch 130, such as a foot lever, a switch on the handpiece or othermeans. When the valve 128 is opened, material from the recirculatingloop 122 is discharged through delivery means 132 at the remote stationand out through a nozzle 134 at the remote station to the target site.Simultaneously, the main unit 120 provides compressed gas or air withentrained abrasive material into the circulating loop 122 to replace thecompressed gas and abrasive material removed from the loop 122 by theopening of the valve 128. Any conventional means, such as a feedbackfrom the individual remote stations 126 or pressure responsive means atthe main unit 120 are used to replace the withdrawn compressed gas andmaterial from the loop 122.

Upon release of the switch 130 at the remote station, each valve 128operates as a relief valve which releases pressure from the deliverysystem 132 at the remote station and channels the release pressure,together with its entrained abrasive material, to a collection unit 134.

It has also been found that the tooth structure and especially theenamel and dentin, can be desensitized or numbed by spraying the toothstructure with an unfocussed spray of the abrasive material laden gasstream. The unfocussed spray is insufficient to actually cut the toothstructure. The precise reason for this phenomenon is unknown.

From the foregoing, it can be seen that the present invention providesmany improvements in dental air abrasive systems. Having described ourinvention, however, many modifications thereto will become apparent tothose skilled in the art to which it pertains without deviation from thespirit of the invention as defined by the scope of the appended claims.

We claim:
 1. An apparatus for cutting tooth structure comprising:a firstsource of abrasive material containing an abrasive material having afirst average size, a second source of material containing an abrasivematerial having a second average size different from said first averagesize, means for creating a gas stream, means for delivering said gasstream to a target site at the tooth structure, means for selectivelyfeeding abrasive material from one of said sources of abrasive materialinto said gas stream upstream from said delivering means so that saidgas stream is laden with abrasive material, wherein said gas stream isof sufficient velocity so that, when laden with abrasive material, cutstooth structure at the target site, wherein said feeding meanssimultaneously feeds abrasive material from said first and second sourceinto said gas stream.
 2. The invention as defined in claim 1 wherein atleast one of said sources contains abrasive material having at least twodifferent colors.
 3. The invention as defined in claim 1 wherein saidabrasive material in said first source has an average size ofsubstantially 20-30 microns.
 4. The invention as defined in claim 1wherein said abrasive material in said second source has an average sizeof substantially 45-55 microns.
 5. The invention as defined in claim 1wherein said means for creating a gas stream comprises a source ofpressurized air.
 6. The invention as defined in claim 1 and furthercomprising at least a third source of abrasive particles different fromsaid first and second source.
 7. An apparatus for cutting toothstructure comprising:a first source of abrasive material containing anabrasive material having a first average size, a second source ofabrasive material containing an abrasive material having a secondaverage size different from said first average size, means for creatinga gas stream, means for delivering said gas stream to a target site atthe tooth structure, means for selectively feeding abrasive materialfrom one of said sources of abrasive material into said gas stream fromsaid delivering means so that said gas stream is laden with abrasivematerial, wherein said gas stream is of sufficient velocity so that,when laden with abrasive material, cuts tooth structure at the target,wherein said delivering means comprises a Y-shaped fluid junctionconnector, a first hose for delivering abrasive material gas stream fromsaid first source to said junction connector, a second hose fordelivering an abrasive material jet stream from said second source tosaid junction connector, and a handpiece connected to said junctionconnector.
 8. The invention as defined in claim 7 and comprising a valvemeans in said junction connector for selectively fluidly opening saidhoses.
 9. The invention as defined in claim 8 wherein said valve meansis pressure actuated.
 10. An apparatus for cutting tooth structurecomprising:a source of abrasive material containing an abrasivematerial, means for creating a gas stream, means for delivering said gasstream to a target site at the tooth structure, means for selectivelyfeeding abrasive material from said source of abrasive material intosaid gas stream upstream from said delivering means so that said gasstream is laden with abrasive material, wherein said gas stream is ofsufficient velocity so that, when laden with abrasive material, cutstooth structure at the target site, and a flavoring added to said sourceof abrasive material.
 11. An apparatus for cutting tooth structurecomprising:a first source of abrasive material containing an abrasivematerial having a first average size, a second source of abrasivematerial containing an abrasive material having a second average sizedifferent from said first average size, means for creating a gas stream,means for delivering said gas stream to a target site at the toothstructure, means for selectively feeding abrasive material from one ofsaid sources of abrasive material into said gas stream upstream fromsaid delivering means so that said gas stream is laden with abrasivematerial, wherein said gas stream is of sufficient velocity so that,when laden with abrasive material, cuts tooth structure at the targetsite, wherein at least one of said sources contains abrasive materialhaving at least two different colors.